Randy,
You need to test mate all those hens and hatch out 12 chicks from each hen, in the process of doing that you'll be creating an eating egg flock and birds that you can cull from out of your test mated group of birds, you need to band each hen and breed her with the yellow legged rooster, after mating stick her in a cage, then collect her eggs when she lays them, if you have one hen banded red, mark her eggs with 1 on the point of the egg, breed your next hen and band her blue, put her in a cage after being mated and when she lays eggs mark her eggs with 2 on the point of the egg, next hen green mark 3 on her eggs, next hen yellow mark 4 on her eggs, you can incubate the eggs all at the same time, the last few days of hatching put all of #1 eggs in a potato sack or tupperware dish covered by a potato sack, do the same with all the eggs from each number, then after they've hatched remove the chicks and band them the same color as the hen they came from is wearing, so all from eggs with 1 would be banded red, 2 would be banded blue, 3 would be banded green, 4 would be banded yellow, then watch them grow, this will help you find which hens don't carry the recessive yellow legs, then those hens you can breed to your rooster and select out cockrels that are good quality and breed them to a yellow legged hen and do the same with the hens eggs for hatching and banding chicks and watch them grow, the ones that don't have the yellow leg are clean of it, then you will have selected another Rooster that is clean of it to use for your flock and also ridded yourself of the recessive yellow legs. I am sure your Rooster is very nice you've been working on Wheatens for several years, he's not going to live forever and you are going to want cockrels from him to use thru the years you have your birds, so the best tribute you can make to him is to breed him to raise better birds from him that are clean of the recessive yellow legged gene.
There's no need to test mate your Rooster, he carrys the recessive gene too, in order for it to express itself in the offspring both the hen and rooster both have to carry the recessive yellow legged gene. Use him with your hens that test clean of it, and when the cockrels grow out to breeding age get Yellow legged hens to test mate them with, that is the fastest way. The chicks have to be over several months old before you can conclusively determine which hens are clean, so 4 months, the leg color can change up to 4 months, not from newly hatched day old chicks. Save the daughter of the
Ebay hen for last to test mate, if the mother tests clean, then test the daughter hen to find out if she's clean of it because it can pass at 50 percent even though you don't see it visually and that way you will know if you can use her as a Clean breeder bird.
I have the same issue with my Bantam Marans split gened group and I only bred one Rooster to one Hen to create those birds, so I know its in both the hen and the Rooster, the split gened group is my F1s those birds bred together are supposed to give me Silver Cuckoo, Gold Cuckoo, Birchen and Black Coppers in my F2's, so far I've got Silver Cuckoo, Birchen, black chicks with mossy brown over their black feathering and Wheaten colored chicks from this mating, and I was not supposed to get yellow chicks, so I have an even bigger problem than you do, I'm not messing with test mating my F1s, the colors I create from them I will test mate and breed to be clean of the recessive yellow legs in the other feather colors I get created. You have a line of Wheatens correctly feather colored, so you need to test mate those hens and get yourself some cockrels from your Rooster and the hens that test clean so that you can test mate those cockrels in about 7 to 8 months with yellow legged hens to decide which cockrels are clean of it to use with your clean birds for a breeding flock of outstanding Wheatens.
Victoria
